In the manufacture of semiconductor chips, variations in process can lead to variations in the characteristics of devices on the chip. In general, devices on the chip can be characterized by their process corner. That is, depending on variations in the manufacturing process, devices formed on a chip, e.g., transistors and so forth, can have different process corners. This means that they operate with slightly different characteristics, e.g., voltage characteristics, operating speed and so forth. In general, process corners may generally be set as: minimum, typical, and maximum; slow, medium, fast; or other such binning characteristics. In the design of a semiconductor chip to ensure that a given chip manufactured from the design will operate as desired, all characteristics such as signal bandwidth, processing speed, and so forth are set such that operation is sufficient at the minimum process corner or worst case scenario.
Similarly, devices of different process corners require different amounts of power to operate. However, to ensure that all semiconductor chips of a given design operate as desired, bias points for the chip design are also set for a worst case scenario (e.g., a slow process, hot temperature and low voltage). These bias points are used to generate currents and voltages on chip that are provided to the various devices to enable their operation. By setting these bias points in the design process at a worst case scenario, power consumption for devices that are at a faster process corner consume more power than needed for proper operation.
In addition to variations in semiconductor chips due to process variations, characteristics of semiconductor performance can also vary due to voltage and temperature. That is, as voltage varies, e.g., a battery voltage from which the device operates, variations in performance can occur. Similarly, as temperature varies from a nominal temperature, device operation can be affected. This is certainly so with regard to semiconductor devices formed according to a complementary metal oxide semiconductor (CMOS) process, as such semiconductor chips can have varying performance and power consumption depending on process, voltage and temperature.
While design considerations may take account of worst cases as discussed above, power consumption can be negatively affected for the majority of chips formed from a given design. Such increased power consumption can negatively impact performance and increase costs, particularly with regard to battery operated devices such as mobile devices including cellular telephones, mobile Internet devices, radios and so forth.